10 Reasons to have green roofs

Green roofs are not neccesarily a new invention. If we omit the oldest turf roof, we can look to 80s to spot the beginning of the modern green roof design. That means green roofs as we know them are with us for more than 40 years.

Yet, despite their many advantages, they still acount for only a small percentage of the overall footprint of cities.

Let’s remind ourselves the greatest advantages so we can translate them to our clients and other involved decision makers.

1) Lifespan

Sun is the most savage enemy of the roofs in hot climates. Layer of greenery protects the roofing against UV radiation, rainfall, snow and debris. By avoiding those externalities, the green roof will last two to three times longer than traditional roof covering. Keep that in mind when you consider the cost for the whole life-cycle of the roof.

2) Insulation

An extra layer of soil and plants helps to regulate the heat. In the summer it absorbs excess heat and in winter it stops it from escaping. This lowers the energy demand which reflects positively on your energy bill.

At the same time, less energy needed to heat or cool the building reduces overall environmental footprint over the lifespan of the building.

3) Sound

Both impact noises such as rain and environmental noises are absorbed by the soil. A 10 cm of green roof lowers the sound impact by up to 5 dB.

4) Aesthetics

We have naturally determined affinity for greenery. Having a green roof provides nicer view for residents above and improves character of the whole neighbourhood.

5) Extra space

Green roofs can be designed as walkable spaces that can extend your garden and provide support for planting herbs and vegetables.

6) Air quality

The vegetation filters some of the pollution and particles present in the air. Leaves can absorb heavy metals such as cadmium, copper and lead. Air pollution above gardens and parks is 80% lower than over the city. At the same time leaf catch the bigger dust particles which are than incorporated into soil substrate or washed down.

In the long run this helps with preventing respiratory problems and thus lowers operating cost of the healthcare system.

7) Water retention

Half of the rainwater that falls onto green roofs is filtered and absorbed by the vegetation, lowering the pressure on the sewage system. This is especially helpful during the peak loads and allows the municipal sewage to be designed smaller and thus less expensive to build and maintain.

Water from green roofs is also cleaner than water from a conventional roof, reducing the maintenance cost for sewage.

8) Microclimate

On the urban scale, green roofs help to mitigate the heat island effect by reflecting sun rays back to the atmosphere and reducing the temperature spikes.

9) Biodiversity

Green roofs contribute to the increase of fauna in the city, such as butterflies, pollinating insect and birds.

10) Real estate value

Who would not pay a bit extra to live in a building that looks awesome and helps the environment at the same time? Considering the symbiosis of all the advantages, it is estimated that on average, green roof boosts the real estate value by up to 7%.

Additional benefits

• Scoring LEED credits
• Quicker reconvalescence of patients
• Potential for grants related to energy efficiency and/ or green roofs.

Conclusion

It is outrageous that with so many benefits, green roofs are still not the base solution. We have resources and technology to design and build great projects, yet we still hesitate.

It is our job to explain these advantages of green roofs to clients, developers and governing bodies and emphasize their long-term benefits.